Electronic messages have become an indispensable part of modern communication. Electronic messages such as email or instant messages are popular because they are fast, easy, and have essentially no incremental cost. Unfortunately, these advantages of electronic messages are also exploited by marketers who regularly send out unsolicited junk messages (also referred to as “spam”). Spam messages are a nuisance for users. They clog people's email box, waste system resources, often promote distasteful subjects, and sometimes sponsor outright scams.
To reach a broad audience, the senders of spam (also referred to as “spammers”) usually generate a huge amount of messages using automated computer programs. There are many existing techniques for filtering spam messages, some of which attempt to identify machine generated messages and block them. Upon receiving a message, the recipient may issue a challenge that is difficult for a computer to answer but easy for a person. For example, the challenge may include a picture of three objects, with the question “how many objects are in the picture?” The sender needs to choose three from a number of available answers and send the answer to the recipient. This type of question, referred to as a human answerable question, is difficult for machines to answer correctly but easy for human beings. The reply is then examined by the recipient's computer. The message is delivered to the recipient if the answer is correct, and processed as spam otherwise. This type of challenge/response scheme incurs significant overhead in for the sender of the email, making email no longer “free” and therefore more difficult for the spammers.
The challenge/response scheme described above is effective for blocking spam messages, but has many drawbacks. For example, since the message is not delivered until the challenge is answered, long delays may result if the sender is not available to answer the challenge right away. Also, the scheme is inconvenient for legitimate users that need to send out messages to new addresses often, for example a business that has many new clients. It would be desirable to have the benefit of the challenge/response scheme for spam blocking purposes, but does not result in long delays in message delivery or excessive burden for the sender.
In one exemplary embodiment of the present invention, a method of registering an electronic-mail (e-mail) sender for the purpose of sending e-mail to a recipient is provided. The e-mail sender receives a challenge message in response to an e-mail message previously sent by the e-mail sender, the challenge message including a machine answerable question. The challenge message is then processed to determine that the message is, a challenge message sent for the purpose of authorizing delivery of e-mail messages. Processing the challenge message in this regard includes identifying an indicator that the message is a challenge message. The message is then parsed to locate the machine answerable question in the challenge message. The question is then analyzed to determine a valid response to the challenge message. A nontrivial amount of resources are required to determine the valid response to the challenge message. The response to the challenge (i.e., the valid response) is then sent that includes an answer to the machine answerable question. Receipt of the response subsequently results in the e-mail sender being registered as a valid e-mail sender. As such, subsequent e-mail messages sent by the e-mail sender will not require sending a valid response to a challenge message.
Another embodiment of the present invention includes a computer-readable storage medium having embodied thereon a program. The program is executable by a computer processor to perform a method of registering an electronic-mail (e-mail) sender for the purpose of sending e-mail messages to an e-mail recipient.
A still, further embodiment of the present invention discloses an electronic-mail (e-mail) server configured to complete a registration process for sending e-mail messages to an e-mail recipient. The e-mail server includes a network interface for receiving a challenge message in response to an e-mail message sent by the e-mail server. The challenge message is received over a communications network and includes a machine answerable question. The server also includes memory configured to store computer-executable instructions for answering the challenge message and a processor configured to execute the instructions stored in memory. When executed, the instructions provide for processing the challenge message to determine that the message is a challenge message for the purpose of authorizing delivery of e-mail messages. Processing the challenge message includes identifying an indicator that the message is a challenge message. The instructions also provide for parsing the message to locate the machine answerable question in the challenge message followed by analyzing the question to determine a valid response to the challenge message. A nontrivial amount of resources are required to determine the valid response. Finally, the instructions provide for sending the valid response via the network interface and communications network. The valid response includes the answer to the machine answerable question and receipt of the valid response results in the e-mail server being registered as a valid e-mail server. As a result, subsequent e-mail messages sent by the e-mail server, will not require sending a valid response to a challenge message.
Another embodiment of the presently disclosed invention provides a method of registering an electronic mail (e-mail) sender for the purpose of sending e-mail messages to an e-mail recipient. The e-mail sender receives a challenge message in response to an e-mail message previously sent by the e-mail sender, the challenge message including a machine answerable question. The challenge message is then processed to determine that the message is a challenge message sent for the purpose of authorizing delivery of e-mail messages. Processing the challenge message in this regard includes identifying an indicator that the message is a challenge message. The message is then parsed to locate the machine answerable question in the challenge message. The question is then analyzed to determine a valid response to the challenge message. A nontrivial amount of resources are required to determine the valid response to the challenge message. A response to the challenge message is then sent to an auditor, which is a different entity than the e-mail recipient. The auditor sends a report concerning the response to the e-mail recipient that identifies that the response includes an answer to the machine answerable question and that the e-mail sender should be registered as a valid e-mail sender. As a result of being registered, subsequent e-mail messages sent by the e-mail sender will not require sending a valid response to a challenge message to the auditor.
In yet another embodiment of the presently disclosed invention, a method of classifying electronic-mail (e-mail) messages from an e-mail sender to an e-mail recipient is disclosed. Through this particular method, a challenge message is generated. The challenge message includes a machine answerable question and for which a corresponding response may be generated by a machine associated with the e-mail sender. Generating the response to the message includes a nontrivial amount of resources with respect to processing the challenge message to determine that the message is a challenge message sent for the purpose of classifying e-mail messages including identification of an indicator that the message is a challenge message; parsing the message to locate the machine answerable question in the challenge message; and analyzing the question to determine a valid response to the challenge message. The challenge message is then sent to the e-mail sender. A determination is later made as to whether a valid response to the challenge message has been sent by the e-mail sender. A valid message results in the sender being classified as a valid sender and excepted from future challenge messages.
Another embodiment of the present invention includes a computer-readable storage medium having embodied thereon a program. The program is executable by a computer processor to perform a method of classifying electronic-mail (e-mail) messages from an e-mail sender to an e-mail recipient.
In a still further embodiment of the present invention, an electronic-mail (e-mail) server configured classify an e-mail message from an e-mail sender to an e-mail recipient is provided. The server includes memory configured to store computer-executable instructions for classifying an e-mail message and a processor configured to execute the instructions stored in memory. When executed, the instructions cause the generation of a challenge message including a machine answerable question and for which a corresponding response may be generated by a machine associated with the e-mail sender. Generating the response requires a nontrivial amount of resources with respect to processing the challenge message to determine that the message is a challenge message sent for the purpose of classifying e-mail messages including identification of an indicator that the message is a challenge message; parsing the message to locate the machine answerable question in the challenge message; and analyzing the question to determine a valid response to the challenge message. The message is then sent via a network interface configured to send the challenge message over a communications network. A valid response to the challenge message includes the answer to the machine answerable question and results in the e-mail sender being classified as a valid e-mail server and excepted from future challenge messages.
Another embodiment of the present invention includes a method of classifying an electronic-mail (e-mail) message from a message sender to a message recipient. A challenge message including a machine answerable question is generated and for which a corresponding response may be generated by a machine associated with the e-mail sender. Generating the response requires a nontrivial amount of resources with respect to processing the challenge message to determine that the message is a challenge message sent for, the purpose of classifying e-mail messages including identification of an indicator that the message is a challenge message; parsing the message to locate the machine answerable question in the challenge message; and analyzing the question to determine a valid response to the challenge message. The challenge message is sent to the e-mail sender and a response is received at an auditor, wherein the auditor is a different entity than the message sender. The auditor is configured to send a report concerning the response to the message recipient that identifies that the response includes an answer, to the machine answerable question and that the e-mail sender should be classified as a valid e-mail sender whereby subsequent e-mail messages sent by the e-mail sender will not require sending a valid response to a challenge message to the auditor.